Effect of Copper Doping Over GdFeO₃ Perovskite on Soot Oxidation Activity

Abstract: A series of Fe substituted (B-site doping) by Cu on the GdFeO₃ perovskite materials (GdFe_1−xCu_xO_3±δ, x = 0 to 0.3) were synthesized using EDTA-Citrate method. The effect of Cu loading on the physio-chemical investigations of the obtained samples was carried out using X-ray Diffraction technique, BET surface area analysis, FESEM/EDS, TEM analysis, XPS, H₂-TPR, and Soot-TPR. The performance of perovskites towards soot oxidation was analyzed in detail using TGA equipment. The results of the XRD pattern shows that upto10 mol% of Cu doping was dissolved into the lattice of GdFeO₃. H₂-TPR results reveal that the samples with Cu loading exhibit the successive reductions of Cu²⁺, Fe³⁺, and Fe²⁺ which implies the presence of multiple oxidation states in the perovskite. This induces the oxygen vacancies in the doped samples (due to charge compensation) leading to an increase in soot oxidation activity. According to the XPS results it was observed that the surface composition of Gd is in +3, Fe in +2 and +3 and Cu in +2 oxidation states. Moreover, the O1s peaks of the doped samples clearly evidenced an increase in adsorbed oxygen species when compared to the un-doped one. Among the doped samples, 10 mol% of Cu loading in GdFeO₃ showed the higher activity of oxygen species. The T_50% (temperature at 50% conversions) of the samples was in the order of GFCu30% < GFCu10% < GFCu5% < GFCu15% < GdFeO₃ < bare soot. Graphic Abstract: [Figure not available: see fulltext.].